Synthesis of Methyl 2, 6-Dimethyl-5-(1', 2'-Dioxo-2'-Ethoxyethyl)-4-(3'-Nitrophenyl)-1, 4 Dihydropyridine -3-Carboxylate

Hantzch's type reaction of methyl acetopyruvate (2a), methyl 3-aminocrotonate (3) and 3-nitrobenzaldehyde (4) led to dimethyl 3-acetyl-6-methyl-4-(3'-nitrophenyl)-2, 5-dicarboxylate (5a) and methyl 2, 6-dimethyl-5-(1', 2'-dioxo-2'-methoxyethyl)-4-(3' nitrophenyl)- 2, 5-dicarboxylate (5a) and methyl 2, 6-dimethyl-5-(1', 2'-dioxo-2'methoxyethyl_4-(3' nitrophenyl)1, 4-dihydropyridine-3-carboxylate (6a) in 26.7 and 9.2% yield, respectively. On the other hand, methyl 2, 60dimethyl-4-(3'-nitrophenyl)-1, 4-dihydropyridine 3-carboxylate (9) was acylated by ethyl oxaly chloride to give methyl 2, 6-dimethyl-5-(1', 2'-dioxo-2'-ethoxyethyl)-4-(3'-nitrophenyl)-a, 4-dihydropyridine-3-carboxylate (6b) in 76.8% yield.